1. Field of the Invention
This invention relates to an improved fabric blind and more particularly but not exclusively to the type of blinds known as Roman blinds which may be used to cover an aperture in a building, for example a window.
2. Discussion of Related Art
The type of blinds typically referred to as xe2x80x9cRoman blindsxe2x80x9d (hereinafter xe2x80x9cRoman blindsxe2x80x9d) conventionally comprise a sheet of fabric material arranged between a top rail (head rail) and a lifting bar. A plurality of equally spaced horizontal bars are attached to the fabric sheet wherein each bar includes two or more guide means such that each guide means is slidably coupled to a respective lifting cord. The lifting cords are fixed to the lifting bar. This arrangement results in a blind which may be raised or lowered by raising or lowering the lifting cords. Raising the lifting cords raises the lifting bar until it engages a first horizontal bar. Both the lifting bar and the first horizontal bar are then raised together via continued raising of the lifting cords until the first horizontal bar engages a second horizontal bar and so on until the blind fabric no longer covers the aperture (i.e. where the lifting bar and each of the horizontal bars are grouped together at the head rail) or until it is in the desired position at which point the blind may be locked in a position by an appropriate lifting cord locking mechanism located in the head rail.
FR-A-2283278, EP-A-0451912 and GB-A-2246593 disclose different arrangements of the horizontal bars that can be used with roman blinds.
However, a major problem with this type of blind is the horizontal bars. These can become distorted by exposure to sunlight or heat which impairs both the operation and the aesthetic appeal of the blind. Efforts have been made to overcome this problem through use of materials such as extruded aluminium or plastics such as polycarbonate. However, these materials are relatively expensive and can have a significant effect on the costs involved in the production of such blinds.
Additionally, where the blind fabric is necessarily a relatively large fabric in order to cover a relatively large aperture, the weight contributed to the overall weight of the blind by the horizontal bars is significant and places additional strain on the lifting cords. In turn these cords must be made either from a stronger, and thus more expensive material, or from a material which has a greater diameter, which is unsightly.
According to a first aspect of the present invention, there is provided a fabric blind including a head rail; a web of fabric material attached at a first end to the head rail; at least one lifting cord extending from the head rail to a second end portion of the fabric material opposite to the first end, the or each lifting cord being secured to the second end portion of the fabric material, and a plurality of guide elements, each of the guide elements being a one-piece construction including a coupling portion slidably coupled to a respective lifting cord and a connecting portion releasably secured to the fabric material, wherein the guide elements are arranged in one or more arrays, such that the or each lifting cord is guided through a respective array of guide elements.
Preferably, the blind includes at least two lifting cords, which may be formed by two or more separate lifting cord elements or a single lifting cord arranged to act as separate lifting cord elements, and at least two respective arrays of guide elements, wherein the number of lifting cords is equal to the number of arrays of guide elements. The term xe2x80x9clifting cordsxe2x80x9d used herein refers to lifting cords which may be formed by a number of separate lifting cord elements or by a single lifting cord suitably arranged to form the desired number of lifting cord elements.
By using a plurality guide elements releasably secured to the blind fabric instead of horizontal bars, the problems associated with the known types of blind are ameliorated or overcome. In order to mimic the use of a horizontal bar whereby the present blind folds in substantially the same way as known blinds, the guide elements are preferably arranged in a grid-like configuration. That is to say, in use, the guide elements are arranged to form a number of columns and rows wherein the (in use) vertical columns of the guide elements guide respective lifting cords and the (in use) horizontal rows of the guide elements mimic the action of a horizontal bar and cause the blind fabric to fold in a way similar to known blinds.
In the present invention, the panels of the material defined by the portion of the fabric web lying between adjacent rows of guide elements have a curved cross-sectional profile even when the adjacent rows of guide elements are separated by the maximum permitted separation. This gives the panels an aerofoil or tear drop shape.
In a preferred embodiment, the fabric web is arranges between a top rail and a lifting bar and the lifting cords are attached to the second end portion of the blind fabric via the lifting bar. The lifting bar has the effect of ensuring that the second end portion of the blind fabric is maintained horizontal during the lifting or lowering of the blind fabric. Moreover, when a blind is allowed to lower without control, and it reaches the maximum extension permitted by the lifting cords, there is a relatively large force exerted on the joints between the lifting cords and the second end of the blind fabric such that the lifting cords may become detached from the blind fabric in such an instance. The use of a lifting bar helps to dissipate that force and greatly reduces the likelihood of the lifting cords becoming detached from the blind fabric.
The blind may include a border or fringe portion of material which extends beyond the second end portion of the fabric web. This border or fringe portion may be integral with the fabric web (i.e. the fabric web and the border or fringe portion are formed as a one-piece construction) or it may be attached to the fabric web. The border or fringe portion may provide an aesthetically pleasing decorative effect.
Thus, in embodiments where the border or fringe portion forms part of the blind fabric material, the or each lifting cord is attached to the fabric material at a point spaced from the (in use) bottom edge of the blind fabric material.
Each of the coupling portions of the guide elements may comprise a loop or eye through which the lifting cord may pass such that the eye or loop is slidably coupled with the respective lifting cord. The guide elements further include a connecting portion extending from the coupling portion. The connecting portion preferably is a T-shaped portion.
The guide elements are secured to the fabric web via the connection portion. This is desirable achieved by xe2x80x9cpunchingxe2x80x9d or urging the connecting portion through the fabric web such that a first part of the connecting portion (e.g. the shaft of a T-shaped connecting portion) extends through the fabric and a second part of the connecting portion (e.g. the cross bar of the T-shaped connecting portion) engages the (in use) front surface of the fabric web and thus resists removal of the guide element from the fabric web. By front surface it is meant the surface of the fabric web which is furthest from the coupling portion of the guide elements and which in use faces away from the building aperture.
Where a T-shaped connecting portion is provided, the cross bar of the T preferably includes flexible resilient arms. This makes it easier to secure the guide element to the flexible sheet element.
Thus, when using a T-shaped connecting portion, the cross bar of the T is positioned adjacent to a surface of the fabric web (the rear surface). A force is then applied to the guide element to urge the connecting portion through the fabric web. The portion of the shaft to which the cross bar in connected penetrates the flexible sheet. The flexible arms are engaged by the fabric web and contrarotate about the shaft until they lie substantially parallel thereto. This configuration of the connecting portion permits it to pass through the fabric web with relatively little resistance. Once the arms of the cross bar are no longer engaged by the fabric web, they snap or spring back to their original configuration, i.e. perpendicular to the shaft. The connecting portion thus releasably secures the guide element to the fabric web as the resilience of the arms of the cross bar resists removal of the connecting portion from the fabric web. Alternatively, a known type of xe2x80x9ctag gunxe2x80x9d may be used, which uses a hollow needle to secure the guide element to the fabric web.
By securing the connection portion of each guide element to the fabric web in this way, a relatively small hole is made through the fabric (i.e. the hole has a diameter which is only fractionally larger than the diameter of the first part of the connecting portion). This hole has a negligible effect on the structural integrity or strength of the fabric web. For example, where the fabric web comprises woven fabric, the act of locating the connecting portion of the guide element through it merely results in a re-alignment of the warp and weft strands of the woven fabric; it does not typically result in the strands being severed. Thus, as the strands are maintained intact, the structural integrity or strength of the woven fabric remains unchanged. By xe2x80x9cstructural integrityxe2x80x9d, it is meant the ability of the fabric web to resist tearing, fraying or other actions that result in damage to it.
Even if the web is non-woven sheet-like material, the relatively small hole made therethrough for the connecting portion would have a negligible affect on the inherent strength or structural integrity of the material. Accordingly, the material is considerably less likely to fray around the hole made by the connecting portion of the guide element.
Moreover, as the hole in the fabric web made by or for the connecting portion of the guide element, it has a diameter substantially the same as the diameter of the shaft of the connecting portion, and thus very little light can pass through the hole. Therefore, the light restricting or suppressing ability of the blind is substantially not affected.
If, as in a preferred embodiment, the cross-bar of the connecting portion is either transparent or coloured a similar colour or tone as the colour or tone of the fabric material, the cross bar becomes generally invisible to the naked eye when the blind is in use. This results in the blind effectively having no visible points or axes about which it may fold, which in turn increases the aesthetic appeal of the blind.
The blind further includes at least one flexible connecting tape disposed between the head rail and the second end of the fabric web, the tape being secured to the fabric web adjacent to, and preferably by, the connecting portions of at least some and more preferably all of the guide elements such that the unfolding of the fabric web is constrained by the connecting tape to a pre-defined maximum spacing between vertically adjacent guide elements.
The connecting tape may be secured flexibly to the fabric web by the connecting portions of the guide elements so that some play is possible. This arrangement permits the flexible connecting tape to move and fold more freely during raising or lowering of the blind. This in turn permits the fabric web to fold and move more freely. Desirably, the first part of the connecting portion, for example the shaft of the xe2x80x9cTxe2x80x9d where a T-shaped connecting portion is provided, passes through the fabric web and extends a short distance from both surfaces of the web. Accordingly, the length of the first part of the connecting portion substantially determines the distance the connecting portion may extend from either surface of the fabric web. The amount of play is determined by this length of the first part of the connecting portion; the greater this length, the more play will be present.
Advantageously the or each flexible connecting tape is a ribbon or similar thin strip of material and the attachment points for securement of the connecting tape to the fabric web are equidistantly spaced along the tape length such that the folds of the fabric web will be similarly equidistantly constrained.
In order that the rear of the blind (i.e. the surface of the blind which faces the architectural opening) presents an aesthetically pleasing appearance, a backing sheet may be included with the blind. The backing sheet is preferably secured to the fabric web such that it covers the lifting cords, the coupling portions of the guide elements, and the flexible connecting tapes. In such embodiments of the invention, the backing sheet may present the same appearance as the fabric web or it may be different, depending upon the desired aesthetic features of the blind. The backing sheet is perfectly secured to the fabric web at points adjacent the guide elements. This results in the backing sheet being capable of folding or unfolding in substantially the same manner as the fabric web. The backing sheet may be releasably attached to the fabric web in order that it may be removed for repair of the lifting cord(s), the guide elements and/or the flexible connecting tapes. In a preferred embodiment, the backing sheet may be releasably attached to the fabric web via I-shaped tags. However, any suitable method or apparatus for releasably attaching one sheet of a fabric material to another may be used, such as for example a hook and loop fastener (e.g. Velcro(copyright)) wherein one part of the fastener is attached to the fabric web and the other part is attached to the backing sheet.